Omron Tateisi Electronics Co.

Keinosuke Imazu

Kenji Ueda

Hisatoshi Nodera

Fumio Kamiya

Hidehiro Tomioka

Disclosed is a power source reset circuit which deactivates a contactless switch for a time interval determined by a delay means so as to prevent any erroneous output from the contactless switch while the output of a power source is unstable immediately after the power source is turned on. The reliability of the delay means is enhanced by the use of a Miller integration circuit which includes a current mirror circuit as a means for amplifying electric current. Furthermore, a switching device may be connected across the capacitor for integration so that the charge in the capacitor may be quickly discharge when the power is turned off, for the purpose of setting the power source reset circuit ready for the subsequent action when the power source is turned on thereafter. This invention is useful in applications where the power source for the contactless switch is frequently turned on and off.

Power source reset circuit for contactless switch

Disclosed is a proximity switch which includes a current feedback time oscillator so that an object in proximity may be detected from the decline in the oscillation output. In order to increase the recovery speed of the oscillation which has dropped as a result of detecting an approaching object, in addition to a first comparison circuit for detecting the object from the oscillation output level, a second comparison circuit is provided for varying the feedback current to the oscillation circuit to the end of maintaining the oscillation level at a certain low level even when the object has come sufficiently close to the proximity switch to otherwise completely terminate the oscillation. By virtue of the increased response speed of the proximity switch, it may be used in an environment where a strong AC magnetic field is present.

Proximity switch

Disclosed is a proximity switch which includes an oscillation circuit whose oscillation output is variable depending on the inductance of a coil so that an object in proximity may be detected from the decline in the oscillation output. Further, the oscillation gain of this oscillation circuit is variable according to an input from an external source. Thus, for the purpose of increasing the recovery speed of the oscillation which has dropped as a result of detecting an approaching object, comparison circuits are provided so that upon reduction in the oscillation output of the oscillation circuit a certain signal is applied to the oscillation circuit to increase its oscillation gain. As a result, even when an object in proximity is detected and the oscillation level is maintained at a certain low level so that the oscillation may be resumed quickly when the object has moved away from the proximity switch. By virtue of the increased response speed of the proximity switch, not only its detection capability is improved but also it is usable in an environment where a strong AC magnetic field is present.

Growing community of inventors

Takatsuki, Japan

Keinosuke Imazu